TECHNOLOGIES
The Polk Audio F/X Wireless Surround uses the
following proprietary Polk technologies:
Dynamic Balance
In 1988, Polk Audio embarked on a long-term research project in partnership with
Johns Hopkins University. The result was a full-field heterodyning laser interfer-
ometer system capable of revealing the microscopic details of entire vibrating sur-
faces (such as a loudspeaker cone) in real-time. This research tool enabled us to
view and analyze the entire vibrating surface of a driver or tweeter. In particular,
we were able to see and understand the resonance that develops on loudspeaker
cones as they move. Modal resonance is a major cause of frequency response
aberrations and other distortions in loudspeakers.
Our new understanding of how resonance develops on speaker components led us
to develop a design technique called Dynamic Balance. Dynamic Balance uses an
analysis of the entire electro-acoustic and mechanical systems to select compos-
ite materials and geometry that reduce resonance. The resulting drive units have
unusual clarity, detail and extension.
Klippel Optimization:
By using a state-of-the-art Klippel Distortion Analyzer, Polk engineers were able
to optimize the woofer’s motor structure, voice coil alignment and suspension
for the best possible performance even at extreme listening levels.
Controlled Dispersion Array
Controlled Dispersion Array technology was developed especially for the
F/X Wireless Surround. Tightly grouped arrays of discrete electrodynamic trans-
ducers, in combination with phase and/or amplitude tapering, produce a radiation
pattern characterized by narrow, steered beams. CDA permits the F/X to project
sound towards reflective surfaces to produce an enveloping, spacious sound field
rich with the spatial cues required for proper localization of surround sound
effects. Further, Polk’s pioneering analysis of head related transfer functions
(HTRF) permits the F/X Wireless surround to perform optimally over a range of
placement locations. HRTFs, an important topic within the realm of psycho
acoustical research, describe how we locate sound sources on the basis of their
perceived frequency response. By embedding magnitude response shaping that
reflects ratios of certain HRTFs, Polk’s F/X Wireless Surround relocates sound
sources from the speaker’s actual position in the room to appropriately elevated
lateral virtual locations. The net result is an exciting surround experience that sim-
ply must be experienced to be fully appreciated.
The dual speaker arrays in the F/X Wireless Surround are oriented towards side-
walls and laterally radiate “narrow” beams of sound. For purposes of properly
reproducing the Surround channels, the dual element arrays operate out of phase.
This creates acoustic nulls — areas in front of and behind the speaker where
sound radiation is greatly reduced relative to lateral acoustic output. The result is
an immersive, spacious surround effect dominated by diffuse lateral reflections,
as opposed to direct sound from the enclosure that would otherwise dictate the
perceived location of the sound source.
To create rear surround effects associated with the dedicated Surround Back
channels of 7.1 program material, we’ve attenuated the Surround Back channels’
gain and added extra latency to ensure that Surround channel spatial cues pre-
cede in-phase SB output. This helps to preserve surround channel spaciousness,
which would be lost if surround back effects were too loud or preceded surround
channel spatial cues. In accordance with an accepted principle of psychoacoustics,
first arriving sound waves determine the perceived location of a
sound source.
Polk Digital Logic
Polk Digital Logic (PDL) is a suite of sophisticated audio processing tools that Polk
uses to create the desired end-result acoustic frequency response shapes that
reflect the appropriate Head Related Transfer Functions (HRTF) ratios for three dis-
crete placement options: Floor, table and shelf. That PDL has been developed to
manipulate not only magnitude response shapes but also the phase and temporal
aspects of multichannel sound reproduction means that the F/X Wireless Surround
can reproduce not only the two discrete Surround channels associated with 5.1
systems but also 7.1 systems’ Surround Back channels. To that end, we’ve attenu-
ated the Surround Back channels’ gain, added extra latency and manipulated inter-
channel phase to ensure that Surround channel spatial cues precede phase-coher-
ent SB output. That SB channels are reproduced in-phase means that appropriate-
ly strong localization cues emerge from the rear of listening area, as intended
for SB effects, but without compromising Surround channel spaciousness. With
regard to the temporal aspects of multi-channel surround sound reproduction, that
first arriving sound waves determine the perceived location of a sound source, (in
accordance with an accepted principle of psychoacoustics), means that SB chan-
nels must be substantially delayed in order to preserve the spaciousness afforded
by room-reflection dominated Surround channel reproduction.
T E C H N I C A L B R I E F
F/X Wireless Surround
Matthew Polk and university researcher
inside laser interferometer lab.
Laser interferometer
images showing
resonance on
peaker cones.
TECHNOLOGIES
The Polk Audio F/X Wireless Surround uses the
following proprietary Polk technologies:
Dynamic Balance
In 1988, Polk Audio embarked on a long-term research project in partnership with
Johns Hopkins University. The result was a full-field heterodyning laser interfer-
ometer system capable of revealing the microscopic details of entire vibrating sur-
faces (such as a loudspeaker cone) in real-time. This research tool enabled us to
view and analyze the entire vibrating surface of a driver or tweeter. In particular,
we were able to see and understand the resonance that develops on loudspeaker
cones as they move. Modal resonance is a major cause of frequency response
aberrations and other distortions in loudspeakers.
Our new understanding of how resonance develops on speaker components led us
to develop a design technique called Dynamic Balance. Dynamic Balance uses an
analysis of the entire electro-acoustic and mechanical systems to select compos-
ite materials and geometry that reduce resonance. The resulting drive units have
unusual clarity, detail and extension.
Klippel Optimization:
By using a state-of-the-art Klippel Distortion Analyzer, Polk engineers were able
to optimize the woofer’s motor structure, voice coil alignment and suspension
for the best possible performance even at extreme listening levels.
Controlled Dispersion Array
Controlled Dispersion Array technology was developed especially for the
F/X Wireless Surround. Tightly grouped arrays of discrete electrodynamic trans-
ducers, in combination with phase and/or amplitude tapering, produce a radiation
pattern characterized by narrow, steered beams. CDA permits the F/X to project
sound towards reflective surfaces to produce an enveloping, spacious sound field
rich with the spatial cues required for proper localization of surround sound
effects. Further, Polk’s pioneering analysis of head related transfer functions
(HTRF) permits the F/X Wireless surround to perform optimally over a range of
placement locations. HRTFs, an important topic within the realm of psycho
acoustical research, describe how we locate sound sources on the basis of their
perceived frequency response. By embedding magnitude response shaping that
reflects ratios of certain HRTFs, Polk’s F/X Wireless Surround relocates sound
sources from the speaker’s actual position in the room to appropriately elevated
lateral virtual locations. The net result is an exciting surround experience that sim-
ply must be experienced to be fully appreciated.
The dual speaker arrays in the F/X Wireless Surround are oriented towards side-
walls and laterally radiate “narrow” beams of sound. For purposes of properly
reproducing the Surround channels, the dual element arrays operate out of phase.
This creates acoustic nulls — areas in front of and behind the speaker where
sound radiation is greatly reduced relative to lateral acoustic output. The result is
an immersive, spacious surround effect dominated by diffuse lateral reflections,
as opposed to direct sound from the enclosure that would otherwise dictate the
perceived location of the sound source.
To create rear surround effects associated with the dedicated Surround Back
channels of 7.1 program material, we’ve attenuated the Surround Back channels’
gain and added extra latency to ensure that Surround channel spatial cues pre-
cede in-phase SB output. This helps to preserve surround channel spaciousness,
which would be lost if surround back effects were too loud or preceded surround
channel spatial cues. In accordance with an accepted principle of psychoacoustics,
first arriving sound waves determine the perceived location of a
sound source.
Polk Digital Logic
Polk Digital Logic (PDL) is a suite of sophisticated audio processing tools that Polk
uses to create the desired end-result acoustic frequency response shapes that
reflect the appropriate Head Related Transfer Functions (HRTF) ratios for three dis-
crete placement options: Floor, table and shelf. That PDL has been developed to
manipulate not only magnitude response shapes but also the phase and temporal
aspects of multichannel sound reproduction means that the F/X Wireless Surround
can reproduce not only the two discrete Surround channels associated with 5.1
systems but also 7.1 systems’ Surround Back channels. To that end, we’ve attenu-
ated the Surround Back channels’ gain, added extra latency and manipulated inter-
channel phase to ensure that Surround channel spatial cues precede phase-coher-
ent SB output. That SB channels are reproduced in-phase means that appropriate-
ly strong localization cues emerge from the rear of listening area, as intended
for SB effects, but without compromising Surround channel spaciousness. With
regard to the temporal aspects of multi-channel surround sound reproduction, that
first arriving sound waves determine the perceived location of a sound source, (in
accordance with an accepted principle of psychoacoustics), means that SB chan-
nels must be substantially delayed in order to preserve the spaciousness afforded
by room-reflection dominated Surround channel reproduction.
T E C H N I C A L B R I E F
F/X Wireless Surround
Matthew Polk and university researcher
inside laser interferometer lab.
Laser interferometer
images showing
resonance on
peaker cones.